Re: SPEC-setosa/hookeri
- To: Multiple recipients of list <i*@rt66.com>
- Subject: Re: SPEC-setosa/hookeri
- From: D* L* <g*@rogerswave.ca>
- Date: Thu, 18 Dec 1997 11:53:10 -0700 (MST)
On Thu, 18 Dec 1997, Bill Shear wrote:
> >The idea that hookeri came from setosa or vis-versa is a somewhat
> >simplistic view of the probable origin of the two species. It seems
> >most likely that there was one species that was spread around the
> >northern parts of North America. When the ice age came, the ice
> >penetrated sufficiently far south in Central Canada that it killed off
> >this species in the middle and the two populations on either side simple
> >grew to be different. Although it would be difficult to prove, the
> >setosa is probably as different, today, from the parent species as
> >hookeri. We must also consider tridentata in the area of Florida,
> >Tennessee and the Carolinas, which is closely related to the other two
> >species and is now separated by much of the east coast area. This
> >species seems to have evolved into a semi-tropical cousin of the two
> >Arctic or semi-Arctic species. Ian, in Ottawa where it is quite
mild - around 0C
>
> Back to setosa/hookeri. As I understand it, the differences between the
> two species are not great, but are consistant. So it seems reasonable to
> assume that whatever the precursor population might have been, it was not
> that different from the two descending species. I'm puzzled, too, by
> tridentata. Perhaps it is not at all related to setosa/hookeri, the loss
> of the standards being just a case of convergent evolution. The plants
> certainly look different, with narrower, tougher foliage, and the bloom
> season is way later. This would be a nice problem to look at using
> biochemical or DNA methods.
> Bill Shear Hampden-Sydney VA 23943
Bill and Ian,
Do you think that the tridentata ancestor may have been shoved down
the middle of the continent by the last glacier and had to evolve
more to adapt to the climate that developed in the south? Did the
glacier(s) come down that far?
Diana Louis <dlouis@dynamicro.on.ca> <- private email
address Zone 4 Newmarket, Ontario, Canada
AIS, CIS, SIGNA, IRIS-L, Canadian Wildflower Soc.
URL for the North American Native Irises web page
http://molly.hsc.unt.edu/~rbarton/Iris/NANI.html
